Ranking and Mapping Human Threats to Marine Ecosystems in the California Current

Quantitative assessment of spatial patterns of all human uses of the oceans and their cumulative effects is needed for implementing ecosystem-based management, marine protected areas, and ocean zoning.

They first surveyed experts in six sub-regions of the California Current to explore geographic variation in the effects of threats. A workshop was held to use decision theory to evaluate the tradeoffs of using expert opinion to assess threats and associated impacts. Data on ecosystems and threats were gathered at resolutions of approximately one square kilometer. By synthesizing information and inferences regarding anticipated impacts of threats, project participants developed a spatially-explicit understanding of the distribution and magnitude of human threats in the California Current. The analysis indicates where protection and threat mitigation are most needed in the California Current and reveals that coastal ecosystems near high human population density and the continental shelves off Oregon and Washington are the most heavily impacted. Climate change is the top threat, and impacts from multiple threats are ubiquitous. Remarkably, these results were highly spatially correlated with the global results for this region (R2=.92), suggesting that the global model[2] provides guidance to areas without local data or resources to conduct similar regional-scale analyses.

Project collaborators are based at University of California, Santa Cruz; The Nature Conservancy; University of California, Santa Barbara; and the Monterey Bay National Marine Sanctuary.